Crystal Structure and Spectroscopic Properties of Bis[trans‐dichlorobis(2,2‐dimethylpropane‐1,3‐diamine)chromium(III)] Tetrachlorozincate

The structure of trans‐[Cr(Me₂tn)₂Cl₂]₂ZnCl₄ (Me₂tn = 2,2‐dimethylpropane‐1,3‐diamine) was determined by a single‐crystal X‐ray diffraction study at 173 K. The analysis reveals that there are three crystallographically independent chromium(III) complex cations in the title compound. The chromium(III) atoms are coordinated by four nitrogen atoms of Me₂tn and two chlorine atoms in a trans arrangement, displaying a distorted octahedral geometry. The two six‐membered chelate rings in three complex cations are oriented in an anti chair–chair conformation with respect to each other. The Cr–N and Cr–Cl bond lengths average 2.0862(2) and 2.3112(6) Å, respectively. The ZnCl₄^2– have slightly distorted tetrahedral arrangement with Zn–Cl lengths and the Cl–Zn–Cl angles are influenced by hydrogen bonding. The resolved absorption maxima in the electronic d–d spectrum were fitted with a secular determinant for a quartet energy state of the d³ configuration in a tetragonal field. It is confirmed that the nitrogen atoms of the Me₂tn ligand are strong σ donors, but the chloro ligands have weak σ‐ and π donor properties toward the chromium(III) ion.     

Crystal Structure and Spectroscopic Properties of trans‐Dibromidobis(propane‐1, 3‐diamine)chromium(III) Perchlorate

The structure of trans‐[Cr(tn)₂Br₂]ClO₄ (tn = propane‐1, 3‐diamine) has been determined by a single‐crystal X‐ray diffraction study at 100 K. The complex crystallizes in the space group P$\bar{1}$ of the triclinic system with two mononuclear formula units in a cell of dimensions a = 6.8220(4), b = 8.86199(9), c = 12.6644(8) Å and α = 77.859(7)°, β = 81.765(6)°, and γ = 77.764(7)°. The chromium atom is in a slightly distorted octahedral environment coordinated by four nitrogen atoms of two tn ligands and two bromine atoms in trans positions. The two six‐membered chelate rings in the complex cations are oriented in an anti chair‐chair conformation with respect to each other. The mean Cr–N(tn) and Cr–Br bonds are 2.093(3) and 2.4681(4) Å, respectively. The crystal packing is stabilized by hydrogen bonds. The infrared and electronic absorption spectral properties are consistent with the result of X‐ray crystallography. It is confirmed that the nitrogen atoms of the tn ligand are strong σ‐donors, but the bromido ligands have weak σ‐ and π‐donor properties toward the chromium(III) ion.     

Synthesis,crystal structure and spectroscopic properties of trans‐dibromidobis(2,2‐dimethylpropane‐1,3‐diamine‐κ2N,N′)chromium(III) perchlorate

The title complex salt, trans‐anti‐[CrBr₂(Me₂tn)₂]ClO₄ (where Me₂tn = 2,2‐dimethylpropane‐1,3‐diamine, C₅H₁₄N₂), was prepared and its structure determined by single‐crystal X‐ray diffraction at 100 K. The asymmetric unit contains three conformationally similar complex cations and three perchlorate anions. In each complex cation, the Cr^III centre is coordinated by four N atoms of two chelating Me₂tn ligands in the equatorial plane and by two Br atoms in a trans‐axial arrangement, to give a distorted octahedral geometry. Interionic contacts are dominated by extensive hydrogen bonding, involving the NH groups of the Me₂tn ligand as donors and the anion O atoms or coordinated Br atoms as acceptors, resulting in two‐dimensional layers in the bc plane. Ligand field analysis based on the angular overlap model, and IR and electronic spectroscopic properties, are also discussed.     

Bis[trans‐dibromo(2,2‐di­methylpropane‐1,3‐diamine‐κ2N,N′)chromium(III)] dibromide hydrogen perchlorate hexahydrate

In the title compound, [CrBr₂(C₅H₁₄N₂)₂]₂Br₂·HClO₄·6H₂O, there are two independent Cr^III complex cations which are conformational isomers of each other. The Cr atoms lie respectively on a center of symmetry and on a mirror plane and have octahedral environments, coordinated by the N atoms of two 2,2‐di­methylpropane‐1,3‐diamine ligands and by two Br atoms in trans positions. The Cr—N and Cr—Br bond lengths are in the ranges 2.078 (3)–2.089 (3) and 2.4495 (9)–2.5017 (9) Å, respectively. The crystal structure consists of two Cr^III complex cations, two Br^? anions, a (ClO₄)^? anion and an [H₁₃O₆]⁺ hydrogen‐bonded cluster cation.     

Mixed-Anion Cu(II) Complexes with 3-(pyridin-2-yl)pyrazole (L), Syntheses and X-ray Crystal Structure of [Cu(L)2 Br]ClO4 (L=3-(pyridin-2-yl)pyrazole)

Reaction of the ligand 3-(pyridin-2-yl)pyrazole (L) with Cu(ClO₄)₂ and CuX₂ (X=Cl, Br, I) gives complexes with stoichiometry [Cu(L)₂X]ClO₄ (X = Cl, Br, I). The new complexes were characterized by elemental analyses and infrared and electronic spectroscopy. The crystal structure of the [Cu(L)₂Br]ClO₄ was determined by X-ray crystallography. The cation complex (i.e. [Cu(L)₂Br]P) contains copper(II) with a distorted trigonal bipyramid geometry with a Br^― ligand occupying an equatorial site. The penta-coordinated metal atom is bonded to two pyridinic nitrogens, two pyrazolic nitrogens, and one bromide anion. The pyrazolic H atoms are hydrogen bonded to Br atoms, resulting in infinite hydrogen-bonded chains running in the b direction. There are π‐π stacking interactions (charge-transfer arrays) between the parallel aromatic rings belonging to adjacent chains that may help to form hydrogen bonding in the coordination geometry around Cu (II).     

Preparations,IR spectra and crystal structures of cyano-bridged bimetallic complexes of zinc(II) and cadmium(II) with tetracyanopalladate(II)

The novel heteronuclear compounds [Zn(hydet-en)₂Pd(CN)₄] (1) and [Cd(hydet-en)₂Pd(CN)₄] (2) {hydet-en: N-(2-hydroxyethyl-ethylenediamine)} have been synthesized and characterized by elemental analyses and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Structural analysis shows that both compounds have shown a polymeric chain, in which the Zn(II)/Pd(II) and Cd(II)/Pd(II) centres are linked by two CN groups. Both zinc and cadmium atoms are six coordinate with two trans cyanide–nitrogen and four hydet-en N atoms in a distorted octahedron arrangement; the palladium atoms in 1 and 2 are four coordinate with four cyanide-C atoms in a square planar arrangement. The chains in both compounds are connected through weak interchain hydrogen bonds, N–H?···?O, N–H?···?N and O–H?···?N, thereby forming a three-dimensional network.     

Crystal Structure and Spectroscopic Properties of cis‐β‐Diazido(1,4,7,11‐tetraazaundecane)chromium(III) Bromide

The new complex, cis‐β‐[Cr(2,2,3‐tet)(N₃)₂]Br (2,2,3‐tet = 1,4,7,11‐tetraazaundecane), was prepared and its structure was determined by single‐crystal X‐ray diffraction. The chromium(III) atom is in a distorted octahedral environment coordinated by four nitrogen atoms of 2,2,3‐tet and two azido ligands in a cis‐β arrangement, with bent Cr–N₃ linkages at the coordinating azide nitrogen atoms. The mean Cr–N(2,2,3‐tet) and Cr–N(azide) bond lengths are 2.084(5) and 2.021(5) Å, respectively. The crystal structure is stabilized by ionic interactions, supported by N–H ··· N(azide) and N–H ··· Br hydrogen bonds. The IR and electronic spectroscopic properties are also discussed.     

Hydrogen bonded networks based on Ni(II)-tetraazamacrocycle (tet-b) complexes: synthesis,isolation and structural characterization of α -[Ni(tet-b)(Cl)](ClO4) and α -[Ni(tet-b)(en)](ClO4)2

Five- and six-coordinate, α-[Ni(tet-b)(Cl)](ClO₄) (1) and α-[Ni(tet-b)(en)](ClO₄)₂ (2) (tet-b?= C-racemic-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) complexes have been synthesized and isolated from the reactions of α-[Ni(tet-b)](ClO₄)₂, which has trans-V (1R,4R,8R,11R,7S,14S or 1S,4S,8S,11S,7R,14R) conformation, with t-Bu₄NCl and ethylenediamine (en), respectively. The complexes have been characterized by X-ray crystallography. The crystal structure of 1 shows a distorted trigonal bipyramidal (TBP) coordination geometry composed of four nitrogen atoms from tet-b and a chloro group with an N₄Cl chromophore about the nickel(II) ion. The complex cations of 1 are assembled by the perchlorate ions via N–H?···?O hydrogen bonding to form 1-D zigzag chains along the [001] direction. The chains are linked through intermolecular hydrogen bonding where the coordinated chloro group of the complex cation forms two-center double hydrogen bonds with the adjacent N–H groups of the macrocyclic ligand along the [100] direction, resulting in a two-dimensional α-network. The crystal structure of 2 shows a distorted octahedral coordination environment consisting of four nitrogen atoms from tet-b and two from en with an N₆ chromophore about nickel(II) ion. The crystal packing analysis shows that the complex cations, α-[Ni(tet-b)(en)]²⁺ are interconnected by perchlorate ions through conventional two-center (N)H?···?O, and bifurcated (N)H?···?O?···?H(N) hydrogen bonding.     

Crystal Structure,Spectroscopic and Magnetic Properties of <Emphasis Type="Italic">Trans</Emphasis>-Difluoro-(1,4,8,11-Tetraazaundecane)Chromium(III) Aquatrichlorozincate

A new complex salt trans-[CrF₂(2,3,2-tet)][ZnCl₃(H₂O)] (2,3,2-tet is 1,4,8,11-tetraazaundecane), is prepared and its structure is determined by single crystal X-ray diffraction using synchrotron data at 100 K. The complex crystallizes in the space group P2₁/c of the monoclinic system with two mononuclear formula units in a cell with dimensions a = 5.6360(11) Å, b = 17.120(3) Å, c = 17.020(3) Å, and β = 94.38(3)°. The chromium(III) ion is coordinated by four N atoms of the 2,3,2-tet ligand in the equatorial plane and two F atoms in a trans axial arrangement, displaying a slightly distorted octahedral geometry. The mean Cr–N(2,3,2-tet) and Cr–F bond distances are 2.0772(11) Å and 1.8930(8) Å, respectively. The crystal packing is stabilized by hydrogen bonding interactions between N–H groups of the 2,3,2-tet, O–H groups of the anion, the F atom, and the Cl atom of the anion. The FT-infrared, UV-visible spectra, and magnetic properties are also described.     

Synthesis and Characterization of A Nickel(II) Complex With Bis(Benzimidazol-2-Ylmethyl) (2-Hydroxyethyl)Amine

This paper reports the synthesis, crystal structure and properties of two new mononuclear nickel(II) complexes, [NiL(phen)][ClO₄]₂(1) and [NiL(bpy)][ClO₄]₂(2), where L is bis(benzimidazol-2-ylmetheyl)(2-hydroxyethyl)amine and phen and bpy are 1,10-phenanthroline and 2,2'-bipyridine, respectively. The crystal structure of 1 ·2EtOH has been determined by single-crystal X-ray analysis. It crystallizes in the monoclinic system, space group C2/c, a= 24.279(2), b= 20.864(2), c= 17.635(1)Å, g = 121.730(2)°, Z= 8, R ₁= 0.064, wR ₂= 0.167. The Ni(II) ion in 1 ·2EtOH is coordinated to three nitrogen atoms and one oxygen atom of the ligand L and two nitrogen atoms of phen to form a distorted octahedron. Spectroscopic properties of 1 and 2 are reported.     

Syntheses,crystal structures,and spectroscopic properties of copper(II) complexes with 3,14-diethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12)docosane

[Cu(L)(NO₃)₂] (1) and [Cu(L)(H₂O)₂](SCN)₂ (2) [L?=?3,14-diethyl-2,6,13,17-tetraazatricyclo(16.4.0.0^7,12)docosane] have been prepared and structurally characterized by single-crystal X-ray diffraction at 100?K. For these constrained macrocycle complexes, copper(II) exists in a tetragonally distorted octahedral environment with the four nitrogen atoms of the macrocyclic ligands and two oxygen atoms from either nitrate or water in axial positions. The macrocyclic ligands in both complexes adopt the most stable trans-III conformation. The Cu–N distances are 2.021(2)–2.047(2)?Å and typical but the axial ligands are weakly coordinating, with Cu–O bond lengths, 2.506(2)?Å for 1 and 2.569(2)?Å for 2, due to the pseudo Jahn–Teller effect. The crystals are stabilized by a 3-D network by intra and intermolecular hydrogen bonds that are formed among the secondary nitrogen hydrogen atoms and nitrate in 1, and intermolecular hydrogen bonds are formed by water and thiocyanates in 2. The electronic absorption and IR spectral properties are also discussed.     

Structural diversity in pseudohalide complexes of cadmium(II) with N-methylthiourea (Metu): Polymeric [Cd(Metu)2(NCS)2]n versus monomeric [Cd(Metu)2(CN)2]

Cadmium(II) complexes, catena-poly[bis(thiocyanato-κN)bis(N-methylthiourea)cadmium(II)], [Cd(Metu)₂(NCS)₂]_n (1) and dicyanidobis(N-methylthiourea)cadmium(II), [Cd(Metu)₂(CN)₂] (2) were prepared and their structures were determined by single crystal X-ray analysis. In 1, the cadmium(II) ion is bound to four sulfur atoms of bridging Metu ligands and two nitrogen atoms of thiocyanate adopting a distorted octahedral environment. In 2, the geometry around cadmium is distorted tetrahedral attained by two cyanide ions and two methylthiourea molecules bound through the sulfur atoms. The crystal structures of both complexes show intra and intermolecular hydrogen bonding interactions. The complexes were also characterized by IR and NMR spectroscopy and the spectroscopic data were discussed in terms of the nature of bonding.     

Caesium cis‐tetrachloridodioxidorhenate(VII)

The title crystal structure, Cs[ReCl₄O₂], consists of cis‐tetrachloridodioxidorhenate(VII) anions and caesium cations. The distorted octahedral anion has nearly C_2v symmetry, with a cis arrangement of the oxide ligands. The Re—Cl bond lengths for the Cl atoms trans to the oxide ligands are affected by the trans influence of the Re—O bonds and are longer than for the Cl atoms cis to the oxide ligands [average of 2.472 (2) Åversus average of 2.322 (2) Å, respectively]. There are ten Cl atoms from six cis‐tetrachloridodioxidorhenate(VII) anions in the neighbourhood of the caesium cation.     

Synthesis,crystal structure,and magnetism of a binuclear Cu(II) complex with double azido as asymmetric basal–apical end-on bridged ligand

A new binuclear copper(II) complex, [Cu₂(μ_1,1-N₃)₂(PP)₂)] ? 2ClO₄ (PP = 2,6-dipyrazol-1-yl-pyridine), was synthesized with double azide as asymmetric end-on bridge ligand and 2,6-dipyrazol-1-yl-pyridine as the terminal ligand. The crystal structure was determined by X-ray crystallography. Cu(II) is located in a distorted square pyramidal geometry, and azide bridges the equatorial-axial linking two Cu(II) atoms with a separation of 3.3595(11) Å. The fitting for the data of the variable-temperature (2–300 K) magnetic susceptibilities by using the Curie–Weiss law gives the Weiss temperature θ = ?7.830 K, indicating a very weak anti-ferromagnetic interaction between the bridging Cu(II) complexes.     

SYNTHESIS AND CHARACTERIZATION OF DIAQUA(3-pTOLYLIMINO-2-BUTANONE OXIMATO)(3-p-TOLYLIMINO-2-BUTANONE OXIME)NICKEL(II) PERCHLORATE

Abstract

[Ni(L^?1)(HL)(H₂O)₂].ClO₄ with a Schiff base ligand L (HL = 3-p-tolylimino-2-butanone oxime) was prepared and structurally characterized by IR, cyclic voltammetry and X-ray diffraction methods. The nickel atom has distorted octahedral coordination consisting of four nitrogen atoms and two oxygen atoms. The equatorial plane is formed by two oxime nitrogen atoms and two imine nitrogen atoms of two Schiff base ligand (L^?1 and HL) with Ni‐ N bond distances between 2.01(1) and 2.11(1)Å. Water oxygen atoms occupy axial positions with Ni‐ O bond distances of 2.06(1) and 2.15(1) Å. The oxime groups in the Schiff base ligands are coordinated to Ni atom through their nitrogen atoms. One asymmetric intramolecular hydrogen bridge between the two oxime groups is found in the title complex.     

The structure of hexafluoroacetone azine bis(triphenylphosphine)platinum

The crystal structure of hexafluoroacetone azine bis(triphenylphosphine)platinum, C₄₂H₃₀F₁₂N₂P₂Pt, has been determined by single-crystal X-ray diffraction techniques. The compound crystallizes in the monoclinic space group C2/c with a 31.155(3), b 13.091(1), c 21.828(2) Å, β 109.23(1)° and Z = 8. Manual diffractometer methods (Cu radiation, λ 1.54050 Å) were used to obtain 5046 reflections with I_net ? 8 counts sec^?1 at 21°C. The structure was solved by the heavy atom method and was refined, including CH₂Cl₂ at occupancy 0.4 on a crystallographic 2-fold axis, by block-diagonal least-squares methods to R = 0.056. Location of the phenyl hydrogen atoms was not attempted. The platinum atom is σ-bonded to one CN of the azine ligand forming a $\text{PtCN}$ three-membered ring. Coordination about platinum consists of a slightly distorted square-planar arrangement of the phosphorus atoms and the bonded carbon and nitrogen atoms of the unsaturated ligand. The observed difference in PtP bond lengths is rationalized in terms of the trans-influence.     

Crystal and molecular structure of the copper(II) Schiff-base complex containing the azo group

From 3-allyl salicylaldehyde and 4-aminoazobenzene (HL), the Schiff-base complex of copper(II) is synthesized and structurally characterized. The crystallographic unit of a CuL₂ (1) single crystal contains two independent molecules of the complex. Coordination polyhedra of copper atoms are slightly distorted squares; azomethine ligands are in the trans-position. The neighboring molecules of the complex are bonded by intermolecular π stacking interactions.     

Synthesis,characterization, crystal structure and thermal analysis of a copper(II) mononuclear compound with 2,6- bis (3,5-dimethyl- N -pyrazolyl)pyridine (bdmpp) and selenocyanate as ligands

A single crystal of the copper(II) compound, [Cu(bdmpp)(SeCN)₂], 2, was obtained and its crystal structure was determined by X-ray diffraction methods. The complex was characterized by elemental, thermal and FTIR analysis. The FTIR analysis of the complex clearly shows the SeCN peaks at 2096 and 2061?cm^?1 which did not exist in the free organic ligand (bdmpp). X-ray analysis showed that 2 crystallized in the monoclinic space group P2₁/c. Cu(II) has a distorted trigonal bipyramidal coordination involving three N atoms from the ligand and two N atoms from the selenocyanate group.     

A new chromium (III) complex containing N-(2-pyridylmethyl)-2-pyrazinecarboxamide, (NPyPzCa): Synthesis,molecular and crystal structure and theoretical electron density analysis

The chromium (III) complex [Cr(NPyPzCa)Cl₂(H₂O)].(CH₃)₂O (1) (NPyPzCa stands for N-(2-pyridylmethyl)-2-pyrazinecarboxamide) has been synthesized and characterized by single crystal X-ray diffraction. The Cr(III) atom exhibits an octahedral geometry due to the coordination of three donor atoms from carboxamide ligand, two chlorine atoms and one water molecule. There is O–H?O hydrogen bonds and also π–π interactions between adjacent pyridine and ?pyrazine rings that seem to be effective in the stabilization of the crystal packing. The ?topological and energetic properties of the electron density distribution of all the metal–ligand ?bonding interactions in this complex have also been calculated and studied at ? several DFT levels. According to the results, metal–ligand bonding interactions belong (from the topological and energetic point of view) to new interactions that represent a mix of closed-shell (ionic) and shared (covalent) characters.     

Synthesis and characterization of mononuclear copper(II) and cadmium(II) complexes with di-(2-picolyl)sulfur

The reaction of Cu(ClO₄)₂·6H₂O and Cd(ClO₄)₂ with di-(2-picolyl)sulfur (dps) leads to the formation of mononuclear complexes [Cu(dps)(H₂O)(ClO₄)](ClO₄) (1) and [Cd(dps)₂](ClO₄)₂ (2). The crystal structure of 1 exhibits a distorted square pyramidal geometry, coordinated by one sulfur and two nitrogen atoms from the dps ligand, one water molecule and one perchlorate oxygen atom. For 2, the environment around cadmium atom is in a distorted octahedron with four nitrogen and two sulfur atoms from the dps ligand. Cyclic voltammetric data show that complexes undergo two waves of a one-electron transfer corresponding to M(II)/M(III) and M(II)/M(I) processes. Spectral and electrochemical behaviors of the complexes are also discussed.